FWIW I went with the x170. Picked it up on ebay for $135. I ran it a lot over the Geezers weekend and never had to change the batteries. I ended up with two DVD's worth of raw video from the one set of batteries.
Here is some video of my hybrid SRT set up
http://www.youtube.com/watch?v=GVu0XEsKW6g
The POV footage was taken with the x170 and the other with an HD hand held camera by a second operator. The x170 being a helmet cam has a lot of "all over the place" and not necessarily steady but that is a function of being a helmet came versus the camera itself.
The good news about the batteries is that they are double a's so if you go dead you just pop two more in. Bad news is you gotta have double a's.
the x170 records in AVI so you dump it straight to Adobe Premier.
I used to worry about not having HD but since most of my vids are watched by people without HD it really doesn't matter.
If I had plenty of cash though I think I'd go with the Contour 1080p. Easier aiming and alignment, greater capacity and uses a common cell phone battery. Tons of car chargers available for that battery as well. Also it appears to have an aluminum body and I think a bit more watertight.
Anyhow, I'm pleased with the x170 as it was cheap and gets me started with helmet cam images.